This invention relates to power injectors, and particularly to injectors of the front loading type, and to the loading of syringes into power injectors, particularly syringes of the flanged or otherwise rear loadable type.
Power injectors are devices used to inject fluids at programmed or otherwise controlled rates or pressures into patients. Important uses include computed tomography (CT) and angiography, where a radiopaque contrast medium is injected into a patient""s vascular system to enhance diagnostic images. With power injectors, a motor-driven ram advances the plunger of a syringe under the control, for example, of a microprocessor to provide control of injection parameters such as flow rate, flow volume and timing. Such injectors are often loaded with sterile empty syringes that are filled by drawing fluid from a supply into the syringe through the syringe nozzle by using the ram to draw the syringe plunger backward. In other situations, the injectors are loaded with prefilled syringes in which the fluid has been packaged in the syringe by media manufacturers.
Syringes of both the empty and the prefilled types are available in more than one design or style. The type of design or style of the empty syringes that are used by a practitioner are typically the choice, in part, of the practitioner and, in part, of the those selecting the injection equipment being used. With prefilled syringes, however, the choices of the practitioner are limited to the designs and styles provided by the prefilled syringe manufacturer, which may be limited due to the need of the manufacturer to submit the syringe and contents to various governmental approval processes. The time and costs involved in such processes as well as the costs of providing alternative syringe containers for each injection fluid product place practical and financial restraints on of the prefilled syringe manufacturer who might be attempting to provide a variety of physical syringe configurations in its product line.
A variety of syringe designs have been developed and are in use for both prefilled and user-fillable syringes. Many such syringes are provided with a radially outwardly projecting flange at their rearward ends which serve to hold or support the syringe against axial motion when force is applied between the flange and plunger by the power ram of the injector. Many syringes with radial flanges on their rearward ends were first developed for use in breech loading or rear loading injectors in which the rear loadable syringe is positioned behind a holder of the injector and translated forwardly, nozzle first, through an opening in the holder, so that the flange or other outwardly extending structure at the syringe rear will seat forwardly against the back surface of the holder. Usually the holder is in the form of a faceplate or door on the injector housing and opens by moving away from the injector housing, either in hinged or turret fashion, for the loading or unloading of the syringe into or from the injector. One such rear loading injector is described and illustrated in U.S. Pat. No. 4,695,271, which is assigned to the assignee of the present application, and is hereby expressly incorporated by reference herein. Injectors of this rear loading type were for many years a standard of the health care industry.
More recently, the assignee of the present invention has provided a front loading injector that receives front loadable syringes. A front loading injector is one in which a front loadable syringe is positioned in front of an opening in an injector holder and loaded into the holder by translating the syringe rearwardly, back end first, into the holder. These front loading injectors have a number of advantages that make them highly preferred. One such advantage is the ability to load the injector manually with a simple one handed motion, by merely rearwardly translating the syringe into an opening in the front of the injector, without opening a loading door, and then twisting or otherwise manipulating the syringe to lock it in place. Such a front loading injector is described and illustrated in U.S. Pat. No. 5,279,569, which is assigned to the assignee of the present application, and is hereby expressly incorporated by reference herein.
Notwithstanding the desirability of using front loadable syringes and front loading power injectors, it is often necessary to utilize prefilled or other syringes, which may be available only in a breech or rear loadable type. To accommodate practitioners in such situations, breech loading capability has been provided for front loading injectors of the type disclosed in U.S. Pat. No. 5,279,569, referred to above, by interchanging the syringe holding head structure of the front loading injector with a breech loading syringe holder that will accept flanged rear loadable syringes. The use of interchangeable heads nonetheless has required the practitioner to resort to the rear loading techniques of the older systems which still have the disadvantages that provided the motivation for their replacement.
Accordingly, there remains a need to provide the advantages of a front loading injector and the capability of using syringes, particularly prefilled syringes, of the rear loadable type, particularly those having flanged or other outwardly extending structure on their rearward ends that function to align or lock the syringe on the injector.
A primary objective of the present invention is to provide a power injector having the capability of being front-loaded with syringes, and more particularly with rear loadable, side loadable, hand operable and other syringes, including prefilled syringes and syringes having locking and aligning structure such as an outwardly extending flange at the rearward end thereof. A more particular objective of the present invention is to provide a front loading injector capable of being front loaded with syringes having flanges at the rearward end thereof and to provide a method of front loading such syringes into a power injector.
A further objective of the present invention is to provide a power injector, such as a front loading injector, with a alternative structure, such as a substitute syringe holder or faceplate, that will adapt an injector to be front loaded with syringes of the rear loadable type, particularly syringes having flanges at their rearward ends.
According to the principles of the present invention, a syringe holder is provided with a syringe receiving opening or cavity therein that is of a size and shape that will receive the rearward end of a breech loadable syringe when the syringe is translated axially rearwardly into the opening. The opening is provided with syringe gripping structure that moves from the periphery of the opening against the body of the syringe, to lock, align and orient the syringe in the opening.
In accordance with the preferred embodiment of the invention, an iris-like syringe holding mechanism is provided, such as, for example, a gripping mechanism including a plurality of jaws is arranged around the opening in a outwardly retracted position on the holder and are linked together. The jaws preferably function in an iris-like fashion, to reduce the size of the opening to that of the syringe body, thereby gripping the body immediately forward of the rearward end of the syringe. Structure on the rearward end of the syringe, such as a radially outwardly extending flange, for example of a type typical of a breech loadable prefilled syringe, is gripped in a slot between the jaws and a stop at the back of the opening, so that the syringe is locked in the opening, is aligned with its axis on the centerline of the opening and is oriented generally perpendicularly to the injector housing wall and parallel to and aligned with the injector ram.
In the preferred embodiment of the invention, the holder is removable, replaceable or exchangeable with holders of other configurations that are provided for supporting syringes of differing shapes or types, or for receiving syringes of the front loadable or rear loadable types. In an alternative embodiment of the invention, the holder with a syringe holding mechanism having iris like holding elements is provided as part of an injector.
With the present invention, breech loadable syringes, particularly prefilled syringes having various configurations of flanges, tabs or other outwardly extending structure at their rearward ends, are capable of being front loaded into and removed from the power injectors, and thereby have all of the advantages of front loadability, including those of high speed syringe replacement, the ability to load or remove a syringe with one hand, and the ability to remove a syringe while injection tubing remains connected to the syringe tip, and other advantages discussed in the incorporated patents cited above. The syringe holder of the present invention is capable of holding syringes with such radially or other outwardly extending structure on their rearward ends as well as syringes of a variety of other configurations, including syringes that lock to the injector at their rearward ends or elsewhere at other locations on the syringe.
These and other objectives of the present invention will be readily apparent from the following detailed description of the drawings.